## Problem Description

The description of this problem is very short. Now give you a string(length N), and ask you the max sum of the substring which the length can't small than M.

## Input

The first line is one integer T(T≤20) indicates the number of the test cases. Then for every case, the first line is two integer N(1≤N≤1000000) and M(1≤M≤N).

Then one line contains N integer indicate the number. All the number is between -10000 and 10000.

## Output

Output one line with an integer.

## Sample Input

2
5 1
1 -2 -2 -2 1
5 2
1 -2 -2 -2 1

## Sample Output

1
-1

## Source

FOJ有奖月赛-2011年03月